Cable drilling tool



March 31, 1942. R, VER QLT 2,278,137

CABLE DRILLING TOOL Filed March 23, 1941) Patented Mar. 31, 1942 UNITED STATES PATENT OFFICE I 2,278,137 CABLE DRILLING 'rooL Merle R. Overholt, South Pasadena, Calif. Application March 23, 1940, Serial No. 325,589 3 Claims; 01. 255-63) This invention relates to the drillingof oil and water wells, and more particularly to that type of drilling known as cable drilling, in which a tool suspended from a cable is raised and dropped in the bore being made for the purpose of cutting the formation being drilled by impact.

The present practice in drilling by the .cable methodis to suspend a swivel from the end of the cable and attach the jars, drill stem and bit thereto.. As the bit is more or less in the shape of a chisel,'it is essential that it be rotated and contact the formation in difierent an-'.

gular aspect at different strokes. Otherwise, the bit has a tendency to drill a fiat hole, which is of insufficient diameter to accommodate the casing run in after the drill. Attempts have been made to rotate the bit by depending upon the twisting and untwisting of the cable as it is subjected to the load of lifting the bit, and relieved thereof upon impact of the bit on the formation, but the thickness of the slush in the hole often prevents this action from being effective in se-' curing good rotation of the bit. This twisting and untwisting is detrimental to the cable, resulting in premature wear thereon, and also causes the bit to peg-leg, that is, to miss strokes, due to the shortening of the effective length of the cable upon twisting.

With the above limitations in the action of drilling bit assemblies in mind, it is an object of this invention to produce a bit which will produce a truly round hole.

It is a further object of this invention to produce a bit which will have positive rotation in the bore between impacts.

It is a further object of this invention to produce a bit structure which will automatically strike the formation at a different rotational position on each impact.

It is a further object of this invention to produce a bit which will rotate in the bore between impacts without wear on the cable.

It is a further object of this invention to produce a drilling bit which will not clog with slush and detritus from the formation.

It is a further object of this invention to accomplish the rotation of the drill without attention from the surface.

This invention possesses many other advantages and has other objects which may be made more easily apparent from a consideration of one embodiment of the invention. For this purpose there is shown a form in the drawing accompanying and forming part of the present specification. This form will now be described in detail, illustrating the general principles of the invention; but it is to be understood that this detailed description is not to be taken in a limiting sense, since the scope of the invention is Figure 1 is an elevation, partly in section, of

a structure embodying one form of my invention;

Figure 2 is a transverse section, taken as indicated by the line 2-2 of Figure Figure 3 is an enlarged fragmentary section of the rachet mechanism; V

Figure 4 is atransverse section through the bit, taken as indicated by the line 44 of Fi ure1;and,

a Figure 5 is a bottom view of the bit taken as indicated by the line 55'of Figure 1. v

Referring more particularly to Figure 1, the shank I0 is provided with a' standard pin -II for attachment to a drill string (not shown). This shank is threadedly secured to the section- [2 by'means' of the male'and female threaded portions l3. The section I2 is bored at M and counterbored at 15 to rotatably receive and provide bearings for the respective cylindrical portion I6 and ll of a spindle to which a drilling bit B is attached. The axial thrust between'the spindle and the section l2, caused by impact of the bit with the bottom of the bore, is transmitted through the engagement of annular shoulders l9 and 20 on the spindle with'the bottom of the counter-bore I5 and the lower end of the section I2.

The upper end of the spindle carries a collar 2|, provided with spring pressed pins 22, projecting from the lower surface thereof but capable of being urged into the collar against the force of the springs 23. This particular feature is also shown in Figure 3. The collar 2| is threaded onto the spindle and is fixedly secured thereto by the nut 24 screwed down on top of it. The uppermost end of the section I2 is provided with a rachet face, shown best in Figures 2 and 3, consisting essentially of a series of arcuate depressions 25, which are of a cross-section shown in Figure 3; These depressions allow the spindle to turn clockwise, but prevent counter-clockwise rotation of the spindle with respect to section I2 due to the engagement of the pins 22 with the steep sides 26 of the depressions. Any other suitable form of rachet may be used to accomplish the intended function instead of the one specifically shown.

The lower end of the spindle is provided with a box 29 accommodating the pin 30 of the bit B. This bit is provided with cutting teeth 35, illustrated as four in number, their bottom ends being sharpened and provided with hardfacing material to penetrate the formation. The outer peripheries of these teeth are provided with flanges 31 which cooperatively with the teeth form channels 38 and also provide an increased amount of metal at the outer ends of the teeth to prevent the bit from wearing under-gauge. The teeth and flanges extend straight for a short distance, as shown clearest in Figure 1, and then twist around the axis of the bit, so that the channels are more or less helical. Such arrangement provides means for driving the bit about in the hole as it falls through the fluid therein. It will also be noted that the channels are shallower at their upper ends, and are narrowest intermediate said ends and the straight portions thereof. It has been found that the particular form of fluid passage illustrated, in cooperation with the flanges, has less tendency to cause rotation of the bit when moving up through the liquid in the wellbore than when the motion is downward.

In order to insure proper operation of the spindle, the interior of the shank l0 may be filled with grease or other lubricant through the fitting 40, the grease being fed to the joint between the spindle and the section l2 by any of the methods commonly employed in roller bit construction for feeding lubricant to spindles and the like. In order that the'grease or lubricant be properly maintained in place, and to prevent the well fluid from entering the joint between the spindle and section 12, the lower extremity of said joint is sealed by a packing ring 40 engageable with the lower end of the section l2 and the spindle sides. The packing may be secured to the assembly by anysuitable means, as for instance by the packer retaining ring 4| secured to the section l2.

In operation, the assembly shown is attached to a drill stem in a string otherwise as in standard practice, and operated exactly as has been done with plain bits, except that no efiort is made, either by twisting the cab-1e or by running to make the bit spin by the slackening and tightening of the cable, to control the position of the bit in the hole. The bit will rotate in a clockwise direction on the downstroke, and any rotation in a reverse direction on the upstroke will be halted by the tightening of the cable and the rachet. The upstroke has a tendency to throw the fluid out by centrifugal force, thus preventing the bit from clogging with mudand assuring an operating region free of detritus in which the bit may reciprocate and turn.

I claim:

1. A cable drilling bit comprising a shank, a series of cutting teeth extending downwardly therefrom, each of said teeth having a lower Vertical portion and an upper helical portion said teeth each having a flange at right angles thereto along its length, thespace between any two adjacent teeth forming a water course partly closed by said flange.

2. A cable drilling bit comprising a shank, a series of cutting teeth extending downwardly therefrom, each of said teeth having a lower vertical portion and an upper helical portion, said helical portion extending from the vertical portion to a portion of'reduced diameter, and said teeth each having a flange at right angles thereto along its length, the space between any two adjacent teeth forming a water course partly closed by said flange and decreasing in cross-sectional area from the bottom of the teeth. to. the uppermost portions thereof.

3. A cable drilling tool comprising a shank, a bit rotatably mounted on said shank, helical water courses in said bit urging its rotation upon movement through the well fluid, said helical water courses'being so formed that their tendency to'cause rotation is greater during downward movement of the bit than during upward movement of the bit, and means preventing rotation of said bit on said shank during upward movement of said tool but permitting rotation on the shank during downward movement thereof. I

MERLE R. OVERHOLT. 

